Research topics: Molecular genetics of virulence in plant pathogenic fungi; biological control of fungal plant pathogens
Molecular genetics of hypovirulence in plant pathogenic fungi; functional genomics for identification and characterization of genes involved in regulation of virulence in the basidiomycete Rhizoctonia solani.
The long-term goal of my work is the biological control of a cosmopolitan, soil-borne plant pathogen, Rhizoctonia solani. Species of Rhizoctonia cause economically important diseases on most of the world’s major field and vegetable crops, fruit and forest trees, turfgrasses, and ornamental plants. Thus, characterization of genetic factors regulating virulence in R. solani could have a significant impact on a wide spectrum of plant related human endeavor.
My research group has shown that particular double-stranded RNA (dsRNA) genetic elements are associated with a dramatically decreased disease-producing capacity (e.g., hypovirulence) in R. solani. Sequencing analysis of these dsRNA’s suggested that they carry an RNA polymerase gene which allows them to replicate in the host cell, but most importantly they carry nucleotide sequences that are genetically related to genes involved in different metabolic pathways. Sequencing analysis of a hypovirulence-associated dsRNA (M2) has enabled me to put forward the following hypothesis: The M2 dsRNA down-regulates the shikimic acid (shikimate) pathway, which is responsible for the synthesis of the aromatic amino acids (AAA). R. solani produces a “toxin” (phenyl acetic acid, PAA) associated with the rhizoctonia disease syndrome in potato. PAA is a derivative of one of the AAA, phenylalanine. Thus, down-regulation of AAA biosynthesis leads to a decreased production of PAA and, in turn, to a diminished degree of pathogenicity (hypovirulence).
It appears that dsRNAs in fungi (and in other organisms) are involved in gene regulation of the host cell. My research program revolves around this hypothesis. Knowledge gained in this area will lead to the development of biocontrol-based strategies of plant disease management that will fulfill the need for sustainable and nonpolluting agricultural practices. Our project is part of a multifaceted, worldwide effort aimed at making agriculture more sustainable, and congruent with the ever-growing societal aspiration to nurture the environment in which we live.
Image Description: Stellos Tavantzis